Hamon and Durability
Some collectors have the impression that the HAMON(刃文) is closely related to the cutting ability but it’s not. If anything the Hamon has something to do with the durability.
The hardened part of the blade is referred to as YAKIBA(焼き刃) and the Hamon is the outline of it and both of them are more breakable than the other parts. In other words, a sword with more Yakiba is less durable.
In fact, according to some records, such swords broke in a battle more often.
SUISHINSHI MASAHIDE(水心子正秀) had used to make a sword with a flamboyant Hamon but once he noticed the problem his style changed.